Vol. 9, Special Issue 7, Part C (2025)

The experiment aimed to evaluate the impact of varying energy and protein levels in total mixed ration on digestibility of nutrients, nutritive value and nutritive intake in crossbred heifer calves. A total of twenty-four crossbred heifer calves (75% Holstein Friesian x 25% Kankrej) with similar growth rate, age, and body weight were randomly allocated to four treatment groups, each consisting of six calves. The calves in groups T₁, T₂, T₃, and T₄ were fed TMR having 12.60% Crude Protein (CP) & 2.028 Mcal Metabolizable Energy (ME)/kg feed, 14.30% CP & 2.131 Mcal ME/kg feed, 15.98% CP & 2.244 Mcal ME/kg feed, and 17.58% CP & 2.307 Mcal ME/kg feed, respectively, for 140 days. The digestibility (%) of DM, OM, CP, EE, NFE, NDF, and ADF of TMRs were non-significantly (p>0.05) different among treatments. The CF digestibility (%) of TMRs fed to crossbred heifer calves significantly (p<0.05) higher in T₁ and T₂ compared to T₃ and T₄. The DCP intake (kg/day, kg/100kg BW, g/kg W^0.75) differed significantly (p<0.05) among the treatment groups, and it increased progressively from lowest T₁ to highest T₄. The DEE and DNFE intake (kg/day, kg/100kg BW, g/kg W^0.75) was significantly (p<0.05) higher in high ME, CP group (T₃, T₄) than low ME, CP group (T₁, T₂). The daily energy (AME, ATDN) intake as significantly (p<0.05) higher in high ME, CP group (T₄) than in ME, CP group (T₁, T₂, T₃). The percent and metabolic body weight basis AME and Actual TDN intake were significantly (p<0.05) higher in high ME, CP group (T₃, T₄) followed by T₂ and lowest reported in the T₁ group.